Bending brake

ABSTRACT

A BENDING BRAKE IN A HAND MANIPULATED TOOL FRO BENDING METAL STOCK AND PARTICULARLY SHEET METAL STOCK TO PRODUCE V-BENDS IN THE STOCK WITH PREDETERMINED RADII OF CURVATURE AT THE BENDS. THE FEMAL DIE MEMBER OF THE BENDING BRAKE COMPRISES AN ANVIL HAVING A V-SHAPED CHANNEL AND THE MALE DIE MEMBER COMPRISES A MANDREL HAVING ON OR A PLURALITY OF V-SHAPED SURFACES EACH CORRESPONDING TO THE V-SHAPED CHANNEL OF THE ANVIL, THE VSHAPED SURFACE OR SURFACES OF THE MANDREL EACH BEING FORMED WITH A TRUNCATED APEX, THE EXTENT OF TRUNCATION OF WHICH DETERMINES THE RADIUS OF CURVATURE PRODUCED IN THE BEND OF THE STOCK. OTHER NOVEL EFFECTS ARE PRODUCED AS A RESULT OF THIS CONTRUCTION OF THE MANDREL.

Oct. 5, 1971 w. DENNINGER 3,610,019

BENDING BRAKE Filed Feb. 16, 1970 3 Sheets-Sheet l J: F/G.

INVENTOR WALTER DENNI NGER ATTORNEY Oct. 5, 1971 w, DENN|NGER 3,610,019

BENDING BRAKE Filed Feb. 16, 1970 3 Sheets-Sheet S 3" i-ha INVENTOR WALTER DENNINGER ATTORNEY United States Patent Office Patented Oct. 5, 1971 3,610,019 BENDING BRAKE Walter Denninger, 63 Central Ave., North Babylon, N.Y. 11703 Filed Feb. 16, 1970, Ser. No. 11,545 Int. Cl. B21j 13/02 U.S. Cl. 72-386 8 Claims ABSTRACT OF THE DISCLOSURE A bending brake in a hand manipulated tool for bending metal stock and particularly sheet metal stock to produce V-bends in the stock with predetermined radii of curvature at the bends. The female die member of the bending brake comprises an anvil having a V-shaped channel and the male die member comprises a mandrel having one or a plurality of V-shaped surfaces each corresponding to the V-shaped channel of the anvil, the V- shaped surface or surfaces of the mandrel each being formed with a truncated apex, the extent of truncation of which determines the radius of curvature produced in the bend of the stock. Other novel effects are produced as a result of this construction of the mandrel.

This invention relates to a bending brake for bending metal stock to produce V-bends therein with different predetermined radii of curvature at the bends.

In producing bends in metal stock such as sheet stock of cold rolled, hot rolled or stainless steel or of other materials such as beryllium, copper and the like, by hand manipulated tools, it is desirable, to meet individual needs or specifications, to produce a V-bend in the metal stock having a specified or predetermined radius of curvature at the bend. This is not obtainable with the use of known bending brakes. Such known bending brakes comprise male and female die members formed with mating and corresponding V-shaped die surfaces. In hand manipulation, such male and female die members, suitably supported on a base, are placed between the jaws of a bench vise and are acted upon by operation of the vise to produce a V-bend in the metal stock. Such known bending brakes are not capable of producing in the metal stock V-bends having a given or predetermined radius of curvature or of producing for different specimens of the stock different predetermined radii of curvature at the bends.

In the operation of such known bending brakes, the metal stock is subjected to strains and stresses in the material thereof by the action exerted thereon by the male and female die members, which produce undesired stretches in the material creating stretch marks therein and resulting, in many cases, in ruptures or breaks in the material. This is due to the fact that the bending action is exerted on the material between three points of the dies, namely the apex edge of the male die member and the two spaced entrant edges of the famale die member.

The prime object of my present invention is the provision of a bending brake operable as a hand tool for bending metal stock, such as sheet steel and other materials, of a number of moderate thicknesses, the purpose of the tool being:

(1) To produce V-bends in the metal stock having a specified or given radius of curvature at the bends and of producing for different stock specimens different predetermined radii of curvature at the bend; and

(2) To produce such V-bends in a manner to reduce stresses and strains in the material that cause stretching of the material, thereby avoiding stretch marks therein and inhibiting such induced effects as ruptures or breaks in the material.

To the accomplishment of the foregoing objects and such other objects as may hereinafter appear, my invention relates to the invention as more particularly defined in the appended claims considered together with the following specification and the accompanying drawings in which:

FIG. 1 is a perspective view of the assembled bending brake of the invention depicting the male and female die members thereof in open position;

FIG. 2 is a top plan view thereof depicting the male and female die members in closed or mating position;

FIG. 3 is a vertical cross sectional view thereof taken in cross-section in the plane of the line 33 of FIG. 2;

FIGS. 4, 5 and 6 are diagrammatic views depicting the structure and characteristics of the male and female die members and illustrating in sequence the operation thereof; and FIGS. 7, 8 and 9 are diagrammatic views of a modification of the male and female die members.

Referring now more in detail to the drawings and having reference first to FIG. 1 thereof, the bending brake of the invention comprises an assembled hand tool generally designated as 10, adapted as hereinafter described to be placed between the jaws of a bench vise for its operation and having as its essential elements a fixed anvil block generally designated as 12 defining the female die member and having a V-shaped channel 14, and a mandrel generally designated as 16 defining the male die member movable with reference to the anvil block 12 in the directions indicated by the arrow 18 and having a V- shaped surface 20 corresponding in angularity to that of the V-shaped channel 14.

The structural and operational characteristics of the anvil 12 and the mandrel 16 are depicted in FIGS. 4, 5 and 6 of the drawings. As shown therein, the V-shaped channel 14 of the anvil block and the V-shaped surface 20 of the mandrel are each defined by walls forming a angle. The anvil 12 is shaped to provide two spaced entrant bending edges 22 and 24 at its V-shaped channel. The V-shaped surface of the mandrel 16 is formed at its entrant end with a truncated apex 26 providing two spaced bending edges 28 and 30 for the V-shaped surface of the mandrel. The extent of truncation of the apex 26 is indicated in these figures by the letter d. As will be described below, with this structure of the anvil and the mandrel, coaction between the mandrel and the anvil operating on metal stock such as the sheet stock 32 Will produce a V-bend in the metal stock with a predetermined radius of curvature 34 at the bend of the stock as shown in FIG. 6 of the drawings.

For enabling different selected radii to be produced at at the bends of a plurality of specimens of the metal stock the mandrel is formed with a plurality of separate V- shaped surfaces, each corresponding to and cooperatable selectively with the V-shaped channel of the anvil. This plurality of separate V-shaped surfaces are each formed with a truncated apex, the extent of truncation of the different for the separate V-shaped surface provided in the mandrel. In the mandrel 16 depicted in the drawings, three additional V-shaped surfaces are formed (in addition to the V-shaped surface 20) designated as 36, 38 and 40 having the truncated apexes 42, 44 and 46 respectively, with different extents or widths of truncation indicated respectively by the letters a, c, and b, respectively.

In the coaction and operation of the anvil 12 and mandrel 16 thus far described an illustrated, in a mandrel having a cross-sectional width of about /2, the extent or width of the apexes illustrated are preferably as follows: a equals .062 or A5 of an inch, b equals .093 or A of an inch, 0 equals .125 or A; of an inch and d equals .187 or of an inch.

With these truncated dimensions the radii of curvature produced at the bend 34 of the stock will be respectively and Sheet stock of various moderate thicknesses, say up to A, may be used in the operation.

Differing from the action exerted on the male and female die members of known bending brakes, the bending operation, stead of being exerted on the stock between three points of the die is exerted effectively on four points of the die members as well as at the center of the male die member or mandrel, namely between the points 28 and 22 and the points 30 and 24 as best depicted in FIG. of the drawings. As a result thereof, stresses and strains on the sheet stock 32 that cause stretching of the material are reduced and thereby so-called stretch marks are avoided and the induced effects on the material such as ruptures or breaks are inhibited or reduced to a minimum.

The mounting of the anvil 12 and the mandrel of 16 in the assembled tool is depicted in FIGS. 1 to 3 of the drawings. The anvil 12 is fixedly mounted on a base plate 48 by means of the bottom positioned head screws 50, and the anvil is also provided with an angle plate 52 fixed thereto by socket head screws 54. The anvil is also preferably provided with a gauge member 56 slideably movable in the directions indicated by the arrow 58 in a bore in the anvil 12 and secured in adjusted positions therein by a knob headed screw member 60. The guide member is formed with an abutment part 57 functioning as a gauge stop for the stock being bent.

The mandrel 16 is receivably mounted in a V-block 62 which latter is secured at its bottom to a plate 64 by means of the screws 66, the bottom of the V-block 62 and the plate 64 being spaced from the base plate 48 (see FIG. 3) to permit movement of the V-block 62 in the directions indicated by the arrow 18, the screws 66 being movable in an opening 68 formed in the base plate 48. The mandrel 16 is removably attachable to the V-block 62 and is secured in position thereto by means of a screw threaded extension 70 and a finger knob 72 engaging the bottom plate 64 as best illustrated in FIG. 3 of the drawings. The mandrel 16 is integrally formed at its top with a finger knob 74. It will be obvious that the mandrel may thereby be rotated to any of its four positions indicated in FIGS. 4 to 6 of the drawings and secured in each such position.

For moving the V-block 62 and the mandrel 16 mounted therein, the V-block 62 is provided with an adjustable bolt 76, the head 78 of which is engageable by a jaw of the bench vise. There is also preferably provided a top plate 80 secured to the spacing legs 82 which are in turn fixed to the base plate 48.

In the operation of the hand-tool bending brake of this invention, bending action exerted on sheet metal stock 32 by the V-shaped surface such as 20 of the mandrel 16 (the male die) entering into and coacting with the V-shaped channel 14 of the anvil 12 (the female die) produces a bend in the stock 32 with a predetermined or selected radius of curvature 34 at the bend of the stock determined by the extent or width of truncation (such as d) of the truncated apex (such as 26) of the V-shaped surface of the mandrel. The anvil, fixed to a support 48, and the mandrel movably mounted on the support, are acted upon by the operation of the jaws of a bench vise made active upon the anvil at one end and on a V-block 62 at the other end, the V-block carrying the mandrel. Different specimens of the stock may be formed with different pre-selected radii of curvature by adjusting the mandrel to present, for action V-shaped surfaces having different widths or extents of truncation of the apexes thereof.

The described hand-tool takes care of normal springback in the metal stock. Where by first closing the tools on. the workpiece with a given truncated apex, the bend 4 obtained is less than (where a 90 bend is desired) or is otherwise unsatisfactory, the mandrel 16 is indexed or turned to a smaller truncated apex or flat, and the closing of the tool is repeated. Also the length of the adjustable bolt or plunger screw 76 may be set so that the vise will close on the mounting plate 48 (and the anvil 12) and act as a positive stop, allowing the adjusted bolt and the parts operated thereby to move in only as far as may be desired to complete the 90 bend, or to make a bend less than 90 if that is desired. The mandrel 16 of FIGS. 4, 5 and 6 is designed as an all purpose tool, for partial bends and offsets and for permitting repeat bends and permitting indexing for four different radii in bends.

In FIGS. 7, 8 and 9, I show a modification of the anvil-mandrel structure designed to permit the making of bends in the metal stock 90 or less in a single operation. In this modification the mandrel 16' is made with a V-shaped surface defining a 60 clearance as best depicted in FIG. 7. In this figure, the other parameters, namely the angles of the other faces of the mandrel as Well as the sizes of certain mandrel faces, ad particularly the Width of the truncation or flat d of the mandrel are indicated. As shown this mandrel has only one working position, namely that with reference to the truncated apex, or fiat d, and is not intended to be indexed for (rotated to) any other position.

In this modification the anvil 12' corresponds to the structure of the anvil 12 in the form of the invention depicted in FIGS. 4 to 6. Otherwise the mandrel-anvil structure of FIGS. 7 to 9 is similar to that of FIGS. 4 to 6, and the corresponding parts are indicated by similar but primed reference characters. With the structure of FIGS. 7 to 9, bends in the stock can be made 90 or less as above indicated in a single operation, the operation depicted in these figures being that for producing a 90 bend in the sheet stock 32' as best shown in FIG. 9.

The use and operation of the bending brake of my invention in its different forms, and the functions and purposes achieved will be clear from the above description of the structure and operation thereof. It will be apparent that changes may be made therein without departing from the spirit of the invention as defined in the following claims.

I claim:

1. A bending brake for bending metal stock to produce a V-bend therein with a predetermined radius of curvature at the bend, comprising an anvil block having a V- shaped channel defining a female die member and a mandrel movable with reference to the anvil block and having a V-shaped surface related to said V-shaped channel and defining a male die member, characterized in that (a) the anvil is shaped to provide two entrant bending edges at its V-shaped channel and (b) the V-shaped surface of the mandrel is formed with a truncated apex providing two bending edges at its V-shaped surface.

2 The bending brake of claim 1 in which the V-shaped channel of the anvil block and the V-shaped surface of the mandrel are each defined by Walls forming a 90 angle.

3. The bending brake of claim 1 for bending metal stock to produce V-bends therein with a plurality of different selected radii at the bends, in which the mandrel is formed with a plurality of separate V-shaped surfaces, each related to and cooperatable selectively with the V- shaped channel of the anvil, and each formed with a truncated apex, the extent of truncation of the apex being different for the separate V-shaped surfaces of the mandrel, thereby enabling different selected radii to be produced at the bends of the metal stock.

4. The bending brake of claim 1, in which the anvil block is fixedly mounted on a supporting base, and the mandrel is mounted in a V-block in turn mounted on the supporting base and movable thereon for movement of the mandrel into and from the anvil block:

5. The bending brake of claim 3, in which the anvil block is fixedly mounted on a supporting base, and the mandrel is mounted in a V-block in turn mounted on the supporting base and movable thereon for movement of the mandrel into and from the anvil block, the mandrel being rotatably adjustable in said V-block for presenting any one of its separate V-shaped surfaces for cooperation with the V-shaped channel of the anvil block.

6. The bending brake of claim 1, in which the V-shaped channel of the anvil block and the V-shaped surface of the mandrel are each defined by walls forming the same angle.

7. The bending brake of claim 1, in which the V- shaped channel of the anvil block and the V-shaped surface of the mandrel are defined by walls forming differing angles.

8. The bending brake of claim 7, in which the V- shaped channel of the anvil block is defined by walls forming a 90 angle and the V-shaped surface of the mandrel is defined by walls forming a 60 angle.

References Cited UNITED STATES PATENTS 2,023,638 12/1935 Lawson 72--413 2,293,184 6/1941 Weissert 72-389 3,029,858 4/1962 Harper 72412 3,094,159 6/1963 Walsh 72389 3,142,174 7/1964 Baker 72-389 3,214,955 11/1965 Voth 72-389 RICHARD J. HERBST, Primary Examiner G. P. OROSBY, Assistant Examiner US. Cl. X.R. 72413, 470 

